PL227655B1 - Desorption method of zirconium and hafnium from an ion exchange resin - Google Patents

Description

The subject of the invention is a method of desorbing zirconium and hafnium from an ion exchange resin after the separation process carried out on it.

Zirconium purified from the accompanying hafnium to a level of <100 ppm is widely used in nuclear technology. Separating the two elements is very difficult and represents one of the biggest challenges in the separation of elements. One of the new effective ion exchange methods for separating zirconium from hafnium is the method using the Diphonix® ion exchange resin, which is the subject of patent PL No. 211 353 and the publication of Smolik, M; et al. Separation of zirconium and hafnium using Diphonix® chelating ionexchange resin Hydrometallurgy 95 (2009) 350-353. Thus, there is known a method of separating hafnium and zirconium on a chelating ion exchange resin containing gem inherently substituted diphosphonic acid groups and appropriately ordered sulfo and carboxyl groups. In this process, a zirconium sulphate solution with a reduced hafnium content is removed from the column, and the ion exchanger column has adsorbed cyirconium and hafnium ions in the ratio [Hf / Zr] greater than in the introduced solution. These ions must then be desorbed from the resin in order, on the one hand, to recover zirconium with increased hafnium content, which can be a raw material for the production of hafnium concentrates and further pure hafnium, and, on the other hand, to prepare the column for multiple use. Both of these factors have a significant impact on the profitability of the process. The regeneration process of the mentioned ion exchanger is difficult due to the very strong affinities of zircon and hafnium ions to it, as well as the tendency of Hf and Zr ions to polymerize and hydrolyze in an insufficiently acidic environment or in the presence of ions that form complex compounds with not very high stability. An additional problem may be the formation of Hf and Zr deposits with the leaching substance and their deposition in the resin grains.

Patent application P-385844 discloses a method of desorbing hafnium and zirconium from the above-described resin with the use of aqueous solutions of ammonium oxalate or sodium ethylenediaminetetraacetic acid. These ligands form stable complexes with hafnium and zirconium and effectively remove them from the resin. However, there is a certain shortcoming of this solution - the formed stable complex compounds are difficult to transform into a form suitable for re-separation by ion exchange (sulphate solutions). Therefore, a significant modification of the existing solution is important.

The method of the invention consists in using a 0.5-3 M sulfuric acid solution for desorption of zircon and hafnium from the chelating ion-exchange resin Diphonix®, and then the residues Zr and Hf are desorbed with 0.25 M ammonium oxalate solution.

The process according to the invention allows quantitatively removed adsorbed Zr and Hf ions from the chelating Diphonix® resin after their separation process. The advantage of the invention is to obtain a regenerated Diphonix® ion exchanger that can be used to purify consecutive portions of zircon from hafnium, the recovery of most (over 50%) of the hafnium-depleted zirconium in a convenient form of a solution of zirconium sulphate (hafnium), which is a substrate for further purification of zircon from hafnium by the mentioned exchange method ionic and obtaining hafnium concentrates which are a substrate for the production of pure hafnium.

P r z k ł a d

An aqueous solution of 2 M sulfuric acid was passed through 6.5 g of Diphonix® ion exchange resin placed in a glass column with an internal diameter of 1.1 cm on which a process of separating Hf and Zr had previously been carried out from a 0.5 M sulfuric acid solution. The leak was collected at a rate of 0.4 ml / min. The process was carried out at room temperature. 130 ml of effluent was collected. Then 10 ml of water was passed through the column and a 0.25 M ammonium oxalate solution was fed to elute the residues Zr and Hf.

71% zirconium and 28% hafnium were desorbed with a 2 M sulfuric acid solution, the rest of the adsorbed metal ions (29 and 71% respectively) were desorbed with 0.25 M ammonium oxalate solution. Thus, a zirconium sulfate solution with reduced hafnium content was obtained

PL 227 655 Β1 raw material for the further purification of zircon from hafnium by the above-mentioned ion exchange method and hafnium concentrate in the form of oxalate containing 8.2% of hafnium in relation to zircon. The mass balance for the tested process is presented in the table.

1 2 3 4 5 The sum of the metal introduced on the column [mg] Sum of metal in the effluent collected from the column in the separation process (0.5M H ₂ SO ₄ ) [mg] The sum of metal in the leakage received in the regeneration process (2M H ₂ SO ₄ + 0.25M (NH4) ₂ C ₂ O ₄ ) [mg] Sum of 2 and 3 [mg] Recovery [%] hafnium 8.95 0.975 2.15 + 5.53 8.655 96.7 zirconium 438 257 152 + 62 471 107.5

Patent claim

Claims (1)

Patent claim 1. The method of desorbing zircon and hafnium from an ion exchange resin containing geminally substituted diphosphonic acid groups and appropriately ordered sulfonic and carboxyl groups, characterized in that 0.5-3 M sulfuric acid solution is used as the desorbent and then the residues Zr and Hf are desorbed by 0 , 25 M ammonium oxalate solution.